No Audio From Source

Hi guys,

I'm trying to convert .mts files to .f4v or some other working format in AME but AME shows that there is No Audio in the source as below.

When I click the encode button, true enough, the output file doesn't have any audio in them.

I'm 100% sure my .mts files have audio in them, I can hear them pretty loudly when played in VLC.

Any idea why and how to resolve this? Thank you.